Optically-active, target-analyte sensitive indicator dyes and compounded materials containing such dyes are widely used in the construction of probes and sensors for quantification and monitoring of target-analytes. Such sensors are particularly suited for use in those situations where nondestructive and/or continuous quantification and/or monitoring of a target-analyte within an enclosed space is necessary or desired as such sensors are amenable to repetitive, non-invasive and contactless interrogation through a variety of common barrier materials.
Sensors employing an optically-active, target-analyte sensitive indicator dye commonly immobilize the dye by embedding the dye within a polymer matrix that is permeable to the target-analyte, hereinafter referenced as an optically-active indicator matrix.
To facilitate handling and use, and avoid contamination of the sample being tested, the optically-active indicator matrix is commonly deposited as a solid-state coating, film, layer or dot on an appropriate substrate support material to form autonomously deployable sensors. See for example United States Published Patent Applications 2011/0136247, 2009/0029402, 2008/199360, 2008/190172, 2007/0042412, and 2004/0033575; U.S. Pat. Nos. 8,242,162, 8,158,438, 7,862,770, 7,849,729, 7,749,768, 7,679,745, 7,674,626, 7,569,395, 7,534,615, 7,368,153, 7,138,270, 6,989,246, 6,689,438, 6,395,506, 6,379,969, 6,080,574, 5,885,843, 5,863,460, 5,718,842, 5,595,708, 5,567,598, 5,462,879, 5,407,892, 5,114,676, 5,094,959, 5,030,420, 4,965,087, 4,810,655, and 4,476,870; PCT International Published Application WO 2008/146087; and European Published Patent Application EP 1134583. Such optical sensors are available from a number of suppliers, including Presens Precision Sensing, GmbH of Regensburg, Germany, Oxysense of Dallas, Tex., USA, and Luxcel Biosciences, Ltd of Cork, Ireland.
Due to a prolific increase in the use of such optical sensors, manufacturers have begun to supply assay vessels and packaging films with an integrated optically-active indicator sensor, thereby facilitating use of such sensors by the end user, particularly those who assay large numbers of test samples on a regular basis. Examples of commercially available assay vessels with an integrated optically-active sensor include microtitter plates available from BD Biosciences of Franklin Lakes, N.J., USA and PreSens—Precision Sensing GmbH of Regensberg, Germany; disposable plastic vials available from Mocon of Minneapolis, Minn., USA and Luxcel Biosciences, Ltd. of Cork, Ireland, and culturing flasks available from PreSense.
Such optically active sensors are usually integrated into assay vessels by depositing a solution or suspension of the optically-active indicator matrix directly onto an inner surface of the assay vessel as a polymeric ‘cocktail’, or adhesively attaching a solid state sensor to an inner surface of the assay vessel.
While constituting a significant advance and finding widespread acceptance within the industry, the manufacture of such sensor-integrated assay vessels is difficult as it requires precision deposition of small aliquots (typically nl and μl quantities) of a viscous cocktail on the inner surface of widely variable and often diminutive assay vessels. Inaccurate or inconsistent size, shape or location of the optically-active indicator matrix, as well as the drying/curing rate of the deposited matrix can result in significant variability in working properties of the resulting sensors. Hence, such sensor-integrated assay vessels are generally expensive to manufacture. Furthermore, use of sensor-integrated assay vessels restricts the end user to use of only those types of assay vessels available with an integrated sensor, thereby reducing the ability to change or adjust experimental conditions in terms of the assay vessel type, size, geometry, alignment, material of construction, etc. Due to high start-up production costs, and strong but limited demand for all but a few types of “sensorized” assay vessels, the industry is unlikely to significantly expand the types of assay vessels available with an integrated sensor.
One alternative for avoiding the drawbacks associated with the deployment of solid-state optically active sensors, is to employ fluid compositions containing the indicator dye in solution or suspension as a liquid or in the form of solid state nano or micro particles which are added to and blended into the samples being tested. This allows the sensor material to be supplied separately from the assay vessels, thereby facilitating a more versatile use relative to the integrated solid state sensors. However, such sensors contaminate the sample and require the use of a much greater quantity of indicator dye as the dye is diluted by the sample.
Accordingly, a substantial need exists for an optically-active, target-analyte sensitive probe capable of quick, easy, flexible and cost effective deployment in a wide variety of assay vessels while consistently and reliably providing sensitive,d accurate and convenient target-analyte measurements.